Technical Field
The present invention relates to a pixel structure of a display device, and in particular, to a pixel structure of a display device with switchable viewing angles.
Related Art
Along with popularization of portable electronic devices such as smart phones and tablet computers, people have more opportunities to use communication software, browse a web page, or process an e-mail while in public spaces, for example, in public transportation such as metro or bus, and in this case, picture information displayed on the electronic device may be viewed by a nearby passenger, and private information of a user such as personal information or a private password may be unwittingly compromised. To solve this problem, an optical privacy filter currently available in the market may protect data on a screen from being viewed by unauthorized individuals; however, it also has problems derived therefrom, such as reduction of the brightness at the front side of the screen and reduction of the sharpness of the display.
In addition to the optical privacy filter, researchers also developed a technology to prevent other persons from viewing content of a display by manipulating light emission angles of liquid crystals. In this method, briefly, a white sub-pixel is added in a single pixel in addition to sub-pixels of three-primary colors of red, green and blue. When a user enables a privacy filtering function, the white sub-pixel is turned on to reduce the visibility of the original sub-pixels of three-primary colors due to the light emission angle; however, when the privacy filtering function is disabled, the white sub-pixel is turned off to avoid color cast, oversaturation, or undersaturation et al.; in other words, merely the sub-pixels of three-primary colors in one pixel are used for light emission, and in this way, the aperture ratio of the screen is reduced. Further, in this method, a plurality of white sub-pixels in a display device is arranged in a regular manner, the light emission angles of interfering pixels may be overly restricted or other persons can view the displayed information on the screen by slightly changing the angles; therefore, there is a need for further improvement in its privacy filtering effect.